Beiträge zur Chemie des Phosphors. 224. Zur Thermolyse von 1,2‐Di‐tert‐butyldiphosphan, 1,2,3‐Tri‐tert‐butyltriphosphan und Tetra‐tert‐butylcyclotetraphosphan

Abstract

Bei der Disproportionierung von 1,2‐Di‐tert‐butyldiphosphan, H(t‐Bu)PP(t‐Bu)H (1), entsteht 1,2,3‐Tri‐tert‐butyltriphosphan, H2(t‐BuP)3 (2), das oberhalb von 100°C zu 1‐(tert‐Butylphosphino)‐2,3,4‐tri‐tert‐butylcyclotetraphosphan, P5(t‐Bu)4H (4), weiterreagiert. Verbindung 4 bildet mit 1 oder 2 unter Verlängerung der P‐Seitenkette das entsprechende 1‐(1,2‐Di‐tert‐butyldiphosphino)‐2,3,4‐tri‐tert‐butylcylotetraphospha, P6(t‐Bu)5H (5). Bei Temperaturen über 170°C disproportioniert 5 in das bis etwa 200°C beständige Tetra‐tert‐butylcyclotetraphosphan, (t‐BuP)4 (3), und das Bicyclo[3.1.0]hexaphosphan P6(t‐Bu)4, aus denen im weiteren Verlauf der Thermolyse die Polycyclophosphane P9(t‐Bu)3 und P8(t‐Bu)6 entstehen. Diese gehen schließlich über noch phosphorreichere und höherkondensierte tert‐Butylcyclophosphane in elementaren Phosphor über. Bei jedem Reaktionsschritt werden wechselnde Mengen der Monophosphanderivate t‐BuPH2, (t‐Bu)2PH und (t‐Bu)3P gebildet. Der angegebene Reaktionsverlauf wird durch die Thermolyseprodukte von reinem 2 und 3 bestätigt.

Synthesis and Structure of a Stable 1,3-Dihydrotriphosphane and Its Thermal Decomposition Leading to the Formation of the Corresponding Phosphine and Diphosphene

“…Addition of an Et 2 O solution of TbtPHLi 11h to a THF solution of dichloroferrocenylphosphine 12 at −78 °C gave a diastereomer mixture of 1 as orange crystals in 73% isolated yield. In sharp contrast to the previously reported 1,3-dihydrotriphosphanes 4a , b , , 1 is stable in the air and on exposure to daylight in the solid state. Moreover, 1 was thermally stable without any decomposition either up to 177 °C in the solid state or at 80 °C in a benzene- d 6 solution in a sealed tube, although 1 has two reactive phosphorus−hydrogen bonds.…”

“…The structural characterization of 4a , b has not been fully accomplished due to their inherent instability, , and the solid state structures have been known for only four triphosphane derivatives, 5a − d , so far (Chart ) …”

“…For example, it was reported by Fehlner in 1968 that P 3 H 5 easily underwent thermal decomposition giving PH 3 and P 2 H 2 with a first-order kinetic constant to the substrate as speculated by a mass spectrometric study . In addition, 1,3-dihydrotriphosphanes (RHP) 2 PR (R = Ph, t -Bu) have been reported as marginally stable examples of triphosphorus hydrides (Chart ). , (PhHP) 2 PPh ( 4a ) was found to undergo a disproportionation reaction at room temperature to give homologues of oligophosphorus hydrides (PhP) n H 2 together with cyclic phenylphosphanes (PhP) n probably via oligomerization of P−H units of 4a …”

“…In addition, 1,3-dihydrotriphosphanes (RHP) 2 PR (R = Ph, t -Bu) have been reported as marginally stable examples of triphosphorus hydrides (Chart ). , (PhHP) 2 PPh ( 4a ) was found to undergo a disproportionation reaction at room temperature to give homologues of oligophosphorus hydrides (PhP) n H 2 together with cyclic phenylphosphanes (PhP) n probably via oligomerization of P−H units of 4a ), having no phosphorus−hydrogen bond, were isolated as stable compounds, it can be concluded that the reactivity of phosphorus−hydrogen bonds inherently gives 1,3-dihydrotriphosphanes thermal instability.…”

Facile synthesis ofcyclo-(P4tBu3)-containing oligo- and pnictaphosphanes

“…The use of 1 as a cyclo-(P4 17 The number of bis-cyclooligophosphanes and bicyclic compounds obtained in pure form is still small, 27,[52][53][54][55][56][57][58][59][60] and to the best of our knowledge only six structurally characterised compounds are known to date, namely P6R4 (R = t Bu, Cp), 52,58 {cyclo-(P5 t Bu4}2, 17 {cyclo-(P4 t Bu3)P t Bu}2, 17 {cyclo-(P4 t Bu3)}2 61 and its pentalane analogue 25 .…”